It is known to obtain power from a single source and to convert to one or more categories of use. For example, U.S. Pat. No. 4,184,197 discloses dc-to-dc switching converters that obtain power from a single source and convert the power to one or more dc voltages. However, these converters do not have the capability of dealing with power extracted concurrently from two or more sources or the capability of extracting power from signals supplied by the sources.
In many applications, it may be desirable to provide power to a load device that has no readily available power source or that for economy of power consumption needs an alternative way of obtaining operating power. For example, a device designed as a retrofit to installed equipment may be unable to tap into the power source of the installed equipment.
There is a need for a power supply apparatus and method that is capable of obtaining power from alternative sources to supply operating power to a load device.